This invention relates to a non-invasive field kit to permit self-determination the relative level of a chemical agent in the urine of a person, particularly a person involved in a health program. In particular, the invention relates to a means to self-test urine using a disposable, indicator test strip having an impregnated reagent area for estimating the amount of urea nitrogen in the urine for determination of the nitrogen balance of a person in a dietary and physical exercise program.
It has been recently recognized that the rate at which an individual absorbs and excretes nitrogen is a good indicator of the individual's nutritional health. Particularly when an individual is involved in a program requiring both dietary control and physical activity, the nitrogen "balance" is considered to be critical in determining whether the individual will have a net physiological gain or loss from a particular physical session.
Nitrogen balance is a term used to define whether an individual is experiencing a net gain or loss in nitrogen, in the form of protein, as a result of his food intake and activity level. Useable nitrogen is added to the body through consumption of protein. Nitrogen is eliminated from the body through various pathways such as urine, feces, perspiration, menstruation and respiration. Other particular situational phenomena can add to normal losses, such as calorie reduction, injury, stress, heavy physical training, profuse sweating and abnormally low quality or quantity of protein intake. As heavy physical training is one known method of substantially altering the body's requirement for nitrogen in the form of dietary amino acids, it is desirable that anyone involved in strenuous athletic activity or in physical training, be conscious of his metabolic rate, and be particularly conscious of the assimilation, utilization and elimination of nitrogen compounds.
Unlike plants which can assimilate nitrogen from fertilizers and in certain cases directly from the air itself, a human is totally dependent upon protein for the daily requirements of nitrogen. The various amino acids that form the intake proteins are utilized for the resulting synthesis of body proteins. Synthesized proteins find their way into the formation of virtually all of the body's tissues, including most prominently muscle tissue, but also in hair, organs and to one degree or another almost in every other particle of the human body. When there is an equilibrium nitrogen balance, the proteins taken in by an appropriate diet replace those proteins that are metabolized or discarded on a daily basis. Dietary protein, therefore, s a critical factor in maintaining a nitrogen balance. Utilization of body protein during the process of athletic training, particularly strenuous activities such as weight training, can also affect the protein balance. Exercise leads to enhanced metabolization of both protein and available carbohydrates.
Clinical methods of determining the urea content and hence nitrogen content of whole blood and plasma have been developed. Furthermore, a reagent strip test method for estimating urea content of whole blood simplifies the test procedure and provides a useful screening test for uremia. The reagent strip test, however, requires at least one or two drops of blood and is therefore an inconvenient method for regular and repetitive testing, particularly for self-testing under less than antiseptic conditions.
Reagent strips such as pH indicators are a known means of providing a convenient method to approximate the acidity or alkalinity of a solution. The urea content of bodily fluids can be detected by reacting the urea with urease which catalyzes the hydrolysis of urea to carbon dioxide and ammonium hydroxide. The ammonium hydroxide quantitatively increases the pH of the solution and this increased pH is measured by color change of a pH sensitive indicator, such as bromthymol blue.
Although past invasive systems are inappropriate for the purposes proposed, this invention devises a means for adapting and utilizing the reagent strip screening test for monitoring nitrogen turnover and approximate balance, enabling a user to adjust his diet and exercise program according to quantitative results of convenient, self-administered urine tests. The urine tests are compared to a personal baseline developed by following a test regimen whereby the user is able to determine whether he or she is in a state of protein surplus or deficiency.